Abstract: The sorption characteristics of the single-component gas(CH₄,N₂,CO₂) and the binary gas with different proportion(80% CH₄+20% CO₂,50% CH₄+50% CO₂,20% CH₄+80% CO₂,80% CH₄+20% N₂,50% CH₄+50% N₂,20% CH₄+80% N₂) on long-flame coal,coking coal and anthracite were studied by means of isotherm adsorption experiment in laboratory.Based on gas content data and gas reservoir pressure data measured through coalbed gas test,some abnormal phenomena taking place in actual production,such as the gas saturation being at the extra-saturated state of 110%,were analyzed in details.The results indicate that in order to obtain the relatively accurate sorption parameters and adsorption isotherm curves,the mixed gas used in isotherm adsorption experiment in laboratory should be matched to the actual coalbed gases in different areas.